Track for snowmobile or the like

ABSTRACT

The disclosure herein describes an endless flexible track for use on a snowmobile or the like, provided with three longitudinally extending rows of sprocket-teeth-receiving openings disposed in laterally spaced relation in the track. A track so constructed may now be used with various types of sprocket wheel arrangements; such a construction enables an antidesynchronization effect on the idler sprocket wheels mounted on the rear axle of the snowmobile.

United States Patent [191 Chaumont TRACK FOR SNOWMOBILE OR THE LIKE [75]Inventor: Guy-Noel Chaumont, Tring-Jonction, Quebec, Canada [73]Assignee: Poly-Traction lnc., Tri-Jonction,

Quebec, Canada [22] Filed: March 2, 1971 [21] Appl. No.: 120,157

[51 1 Int. Cl. ..B62d 55/24 [58] Field of Search ..305/35 EB, 37, 38;180/5 R [56] References Cited UNITED STATES PATENTS [4 1 Jan. 23, 19733,480,339 11/1969 Kell ..305/35 EB 3,623,780 11/1971 Kell ..305/383,582,155 6/1971 Marie: ..l.305/38 3,612,625 10/1971 Huber ..305/38Primary Examiner-Richard J. Johnson Attorney-Cushman, Darby & Cushman[57] ABSTRACT 3,580,647 5/1971 Richards ..305/35 E8 9 Claims, 14 DrawingFigures 20 Y 78 72 f U ea 86 :3": [E/III PATENTEDJAH 23 1975 SHEET 2 BF3 lNl/ENTOR Noel CHAUMONT 7'7'0F/VEIS JMAW 02% mm TRACK FOR SNOWMOBILEOR THE LIKE The present invention relates to tracks for selfpropelledvehicles; more'particularly, this invention pertains to an improvementin the manufacture of an endless flexible track of the type normallyused for driving a snowmobile or the like.

At present, the track used for propelling this type of snow vehicle iscommonly made of a thin and elastomeric material having a generally flatinner surface and a corrugated outer surface. The endless track islooped around one or two idler sprocket wheels and one or two drivesprocket wheels, the teeth of the sprockets being received in one or twolongitudinal rows of openings extending through the track; the numberand size of sprocket wheels on the front drive axle and the number andsize of sprocket wheels on the rear idler axle depend upon the intendeduse and desired performance of the vehicle; for example, someconventional snowmobiles have one front drive sprocket and onerear'idler sprocket, in whichcase the track used consists of onecentrally disposed longitudinal row of sprocket-teeth-receivingopenings; other snowmobiles may consist of two front drive sprockets andof two rear idler sprockets, in which case the track used will beprovidedwith a pair of laterally spaced Iongitudinal rows ofsprocket-teeth-receiving openings. Furthermore, whether one or twosprockets are used on each axle, the size and the number of the sprocketteeth will be a factor in the final design of the sprocket arrangement;for instance, a track with a single row of openings will be engaged by asprocket with larger and thus stronger teeth than would a track with tworows of openings for the same amount of torque which is to. betransmitted by the front axle of the snowmobile. Therefore, the use ofpresent-day snowmobile tracks is limited to the exact sprocketarrangement existing on a particular snowmobile and track replacementcan'only be made by a track of similar construction'of that of thereplaced track.

Another disadvantage of present-day snowmobile tracks is that, since thedrivesprocket wheel'on the front axle engages the same longitudinal rowof openings as does the idler sprocket wheel on the'rear axle, there'isa-desynchronization between front and rear sprocket teeth engaging theopenings whenever the elastomeric track is elongated under considerableThe present invention relates to an endless driving track for use in asnowmobile or the like comprising, in its broadest aspect, an outerground-engaging surface, an inner surface, afirst longitudinallyextending row of aligned sprocket-teeth-rec'eiving openings centrallylocated in the track; and second and third longitudinally extending rowsof aligned sprocket-teethreceiving openings located in the track inlaterally spaced relation on either side of the first central row.

By providing an endless track with three rows ofsprocket-teeth-receiving openings, tracks presently in use, whendefective, may be replaced by a track made in accordance with thepresent invention without having to alter the sprocket arrangementalready present on the snowmobile; the present track will substitutetracks driven by one front sprocket wheel and one rear sprocket wheel aswell as tracks driven by a pair of front sprocket wheels and a pair ofrear sprocket wheels.

Other objects and advantages will become apparent from the followingdescription of'one embodiment of the track with reference to theaccompanying drawings wherein:

FIG. 1 is a fragmentary plan viewof one form of a track constructed inaccordance with the present invention;

FIG. 2 is an exploded view showing the layup of a track similar to theone shown in FIG. 1;

5 FIG. 3 is a transverse cross-sectional view taken along lines 3-3 ofFIG. 1;

centrifugal strain. Furthermore, on tracks having two I laterally spacedrows of openings, a further desynchronization is added to the aforesaideffect due to transverse strain on the track and to the distortionresulting therefrom. This desynchronization effect tion of which enablesnew types of sprocket arrange-.

ments.

It is a further object of this invention to provide an endless flexibletrack for snowmobiles or the like which enables ananti-desynchronization action when in driving engagement around driveand idler sprocket wheels.

FIG. 4' is a cross-sectional view taken along lines 4- 4 of FIG. 1;

FIG. 5 is a fragmentary cross-sectional view taken along lines 5-5 ofFIG. 1;

FIG. 6 is a fragmentary cross-sectional view taken along lines 6-6 ofFIG. 1;

FIG. 7 is a top plan view of the clip used in the track shown in FIG. 2;

FIG. 8 is a side elevational view of the clip shown in FIG. 7;

FIG. 9 is a perspective view of the clip shown in FIGS. 7 and 8; and vFIGS; 10-14 illustrate different front and rear sprocket wheelarrangements made possible with the present invention.

Referring to FIG. 1 of the drawings, a portion of an endless flexibletrack embodying the present invention, is shown and is generally denotedby the numeral 15. The trackhas an outer ground-engaging surface 16provided with a tread, the configuration of which may adopt variouspatterns of corrugation. The'track has also a generally flat innerperipheral surface 18 (see FIG. 3) to receive the wheels of thesnowmobile suspension assembly (not shown). The track 15 illustrated inFIG. I has three longitudinally extending rows of alignedsprocket-teeth-receiving openings 20, 21 and 22 that divide the track infour longitudinally extending portions 24, 25, 26 and 27. A first row 21is centrally located in the track and second and third rows 20 and 22are located in laterally equidistantly spaced relation on either side ofthe central row 21. One important feature of the present invention isthat the track illustrated in FIG. 1 may be used with presently knowntypesof sprocket arrangement on snowmobiles; it may be used on asnowmobile having one front sprocket wheel and one rear sprocket wheel,in which case only the row of openings 21 would be engaged by bothsprockets; it may also be used on a snowmobile having two laterallyspaced front sprocket wheels and two laterally spaced rear sprocketwheels, in which case only the rows of openings 20 and 22 would beengaged by the four sprockets. The area of each opening 21 is shownlarger than that of each opening 20 or 22 since snowmobiles equippedwith only one front and one rear sprocket wheel generally require largersprocket teeth than that required when a pair of front and rear sprocketwheels are used. In addition to suit presently known sprocketarrangements, the present track enables new sprocket arrangements and anantidesynchronization between sprockets; these advantages willhereinafter be described with reference to FIGS. -14.

The present invention may be embodied in all types of track layup. Onenovel track made possible with the present invention is illustrated inFIGS. 1-9. FIG. 2 shows a typical layup for forming such a track, thedetailed specification of each material being known by the personskilled in this art. The outer continuous layer 30 is of rubber followedby a discontinuous layer of woven nylon 32, a second continuous layer ofrubber 34, two spaced layers of longitudinally extending steel cables 36or the like, such as polyester and fiberglass, underneath which are twospaced layers of woven nylon 38. A reinforcing member 40 is incorporatedin the track and is transversely disposed thereof. In the present case,the reinforcing member 40 consists of a flat rigid bar of rectangularcross-section with three raised portions 42, 43 and 44 and two remaininglower portions 45 and 46. The end raised portions 42 and 44 arerespectively embedded in the track between a layer of nylon 48 and alayer of rubber 50. A layer of rubber 51 extends over the middle raisedportion 43 and the two lower portions 45 and 46. The inner surface ofthe track is finished with a discontinuous layer of nylon 52 and adiscontinuous layer of rubber 53. Clips 54 are mounted on the raisedportions of the reinforcing member 40 and are located in thelongitudinal rows of openings 20, 21 and 22 adjacent the openings. Thedifferent layers of rubber and nylon shown in FIG. 2 with thereinforcing member. 40, are usually cured under pressure in the mouldsof a vulcanizer to form an endless elastomeric track, a cross-section ofwhich is shown in FIG. 3. During the vulcanization, the material willflow underneath such area as inclined portions 56 of the reinforcingmember 40 so as to form a continuous generally flat inner surface.

FIGS. 7-9 illustrate one type of clip which can be fixed on thereinforcing member 40. Other types are shown in the inventors CanadianPat. No. 833,436 issued Feb. 3, I970. The clip 54 is made of metal andconsists of a tubular member with one longitudinal split; the clip iscrimped on the reinforcing member 40 and its opposite ends 58 arefurther squeezed to take the shape of the reinforcing member 40; in thisfashion, the clip cannot rotate about the bar 40. Referring to FIGS. 4and 6, the metal clip 54 is partially embedded in the elastomericmaterial where its outside lateral walls 60 and 62 form wear surfacesfor the teeth of the sprockets engaging the openings. The undersurface64 may be recessed relative to the inner surface 18 or in the same planethereof.

Referring to FIGS. 1 and 5, the outer surface of the track has a treaddesign consisting ofa series of longitudinal ribs 66, transverse ribs 68and side ribs 70 extending at an angle to the other ribs; this tread andother similar treads provide the track with transverse and longitudinaltraction. To provide tensile strength to the track, a plurality ofcable-type elements 36 are placed adjacent the central row of openings21; these elements are made of the inextensible material such as nylon,steel, polyester, fiberglass or other suitable material.

Referring to FIGS. 10-14 of the drawings, there are shown various knownand novel sprocket arrangements made possible with a track made inaccordance with the present invention, the arrow indicating the forwarddirection of travel of the snowmobile. Track 15 may be used on asnowmobile provided with two front sprocket wheels 72, 74 joumalled onthe front drive axle 76 and two rear sprocket wheels 78 and 80journalled on the rear idler axle 82 (FIG. 10). Track 15 may also beused on a snowmobile provided with one front sprocket wheel 84 joumalledon the drive axle 76 and one rear sprocket wheel 86 journalled on theidler axle 82 (FIG. 12). These two types of sprocket arrangements arethose generally found on present-day snowmobiles. One important featureof the present invention is that the track made in accordance with thepresent invention enables sprocket arrangements which haveantidesynchronization effect. As explained above and referring moreparticularly to FIGS. 10 and 12, because front sprocket wheel 72 and 74(or drive sprocket wheel 84) engage the same longitudinal row ofopenings as do the rear sprocket wheels 78 and 80, respectively, (orrear sprocket 86), there is a desynchronization between the sprocketwheels engaging the same row of openings whenever the elastomeric trackis elongated under considerable centrifugal strain. There results fromthis effect a deformation and an excessive wear of the sprocket engagingsurfaces. Referring to FIG. 11, because the track is provided with threerows of openings, it is now possible to have a sprocket arrangementconsisting of one front sprocket 84 engaging the row of openings 21 andtwo rear sprockets 78 and 80 engaging respectively the rows of openings20 and 22. To obviate the desynchronization effect, each rear sprocket78, 80 is capable of running independently from one another; this isachieved by inserting a decoupling member 88, such as a ball bearingconnection or the like which will divide the rear axle into twoindependently rotating shafts 90 and 92 (FIGS. 11 and 13). The sprocketarrangement illustrated in FIG. 14 shows that two decoupling members 88and 88 are used so that the three rear sprockets 78, 80 and 86 mayrotate independently of one another. In a similar fashion, there may beprovided a single fixed rear axle with the respective rear sprocketwheels mounted to rotate freely about the fixed axle. All these sprocketarrangements would be recommended for different usage; for instance, thesprocket arrangement shown in FIG. 11 would be recommended for highspeed snowmobiles whereas the sprocket arrangement of FIG. 13 could bemounted on a snowmobile having a high performance engine and thesprocket arrangement of FIG. 14 would be recommended for towing purposesof 24-hour races.

Various other embodiments of the present invention can be apparent tothose skilled in the art without departing from the spirit and scopethereof. It is therefore wished to have it understood that thisinvention is not limited in interpretation except by the terms of thefollowing claims.

What I claim is:

I. An endless driving track for use in a snowmobile or the likecomprising an outer ground-engaging surface, an inner generally flatsurface, a first longitudinally extending row of alignedsprocket-teeth-receiving openings centrally located in the track, andsecond and third longitudinally extending rows of alignedsprocket-teeth-receiving openings located in the track in laterally andequidistantly spaced relation on either side of the first central row ofopenings, the area of the openings of said central row of openings beinglarger than that of the openings of said second and third rows.

2. An endless driving track as defined in claim 1, further comprising aplurality of equidistantly spaced reinforcing members extendingtransversely of said track and traversing said first, second and thirdrows of openings between adjacent openings, each of said reinforcingmembers having raised portions embedded in said track between saidadjacent openings, the remaining portions of said reinforcing memberbeing generally flush with the inner surface of said track.

3. An endless driving track as defined in claim 2, wherein a pair oflayers of closely spaced longitudinally extending cable-like elementsare incorporated in said track on each side of said central row ofaligned openings and above said remaining portions of said reinforcingmembers.

4. An endless flexible track as defined in claim 3, further comprisingthree laterally spaced clips secured to each of said reinforcingmembers, said clips being partially embedded in said track and locatedin said rows between adjacent openings, sad clips forming front and rearwear surfaces in said openings.

5 An endless flexible track as defined in claim 4, wherein said rows ofopenings divide said track in four longitudinally extending portions ofelastomeric material, said material consisting of first, second andthird layers of rubber material and first and second layers of wovennylon interposed between said first,

second and third layers or rubber, said layers of rubber and woven nylonextending over said reinforcing member, said elastomeric materialfurther comprising in opposite edge portions of said track, fourth andfifth layers of rubber material separated by a third layer of wovennylon.

6. In a snowmobile or the like having a front drive axle supporting atleast one driving sprocket wheel and having a rear idler axle supportingat least one sprocket wheel, an endless driving track looped around saiddrive sprocket wheel and said idler sprocket wheel comprising an outerground-engaging surface, an inner generally flat surface, a firstlongitudinally extending row of aligned sprocket-teeth-receivingopenings centrally located in said track, and second and thirdlongitudinally extending rows of alignedsprocket-teethreceiving openingslocated in the track in laterally and equidistantly spaced relation oneither side of said first central row, the area of each opening of saidcentral row being larger than that of the openin s of said second andthird rows, the teeth of the sproc et wheel engaging the openings ofsaid central row being substantially bigger than the teeth of saidsprocket wheels engaging the second and third rows of openings.

7; In a snowmobile as defined in claim 6, wherein said front drive axlesupports one sprocket wheel for rotation therewith, the teeth of saidsprocket wheel engaging the central row of openings: wherein the rearidler axle supports a pair of sprocket wheels, the teeth of which engagethe second and third rows of openings, respectively; and furthercomprising means on said rear axle for causing said rear sprocket wheelsto rotate independently from one another thereby providing ananti-desynchronization effect therebetween.

8. In a snowmobile as defined inclaim 7, wherein said front drive axlefurther supports for rotation therewith a pair of sprocket wheels, theteeth of which respectively engage the second and third rows ofopenings.

9. In a snowmobile as defined in claim 8, wherein said rear axle furtherincludes a third sprocket wheel engaging the central row of openings andmeans for causing said third sprocket wheel to rotate on said rear axleindependently of said other sprocket wheels mounted on said rear axle.

1. An endless driving track for use in a snowmobile or the likecomprising an outer ground-engaging surface, an inner generally flatsurface, a first longitudinally extending row of alignedsprocket-teeth-receiving openings centrally located in the track, andsecond and third longitudinally extending rows of alignedsprocket-teeth-receiving openings located in the track in laterally andequidistantly spaced relation on either side of the first central row ofopenings, the area of the openings of said central row of openings beinglarger than that of the openings of said second and third rows.
 2. Anendless driving track as defined in claim 1, further comprising aplurality of equidistantly spaced reinforcing members extendingtransversely of said track and traversing said first, second and thirdrows of openings between adjacent openings, each of said reinforcingmembers having raised portions embedded in said track between saidadjacent openings, the remaining portions of said reinforcing memberbeing generally flush with the inner surface of said track.
 3. Anendless driving track as defined in claim 2, wherein a pair of layers ofclosely spaced longitudinally extending cable-like elements areincorporated in said track on each side of said central row of alignedopenings and above said remaining portions of said reinforcing members.4. An endless flexible track as defiNed in claim 3, further comprisingthree laterally spaced clips secured to each of said reinforcingmembers, said clips being partially embedded in said track and locatedin said rows between adjacent openings, sad clips forming front and rearwear surfaces in said openings.
 5. An endless flexible track as definedin claim 4, wherein said rows of openings divide said track in fourlongitudinally extending portions of elastomeric material, said materialconsisting of first, second and third layers of rubber material andfirst and second layers of woven nylon interposed between said first,second and third layers or rubber, said layers of rubber and woven nylonextending over said reinforcing member, said elastomeric materialfurther comprising in opposite edge portions of said track, fourth andfifth layers of rubber material separated by a third layer of wovennylon.
 6. In a snowmobile or the like having a front drive axlesupporting at least one driving sprocket wheel and having a rear idleraxle supporting at least one sprocket wheel, an endless driving tracklooped around said drive sprocket wheel and said idler sprocket wheelcomprising an outer ground-engaging surface, an inner generally flatsurface, a first longitudinally extending row of alignedsprocket-teeth-receiving openings centrally located in said track, andsecond and third longitudinally extending rows of alignedsprocket-teeth-receiving openings located in the track in laterally andequidistantly spaced relation on either side of said first central row,the area of each opening of said central row being larger than that ofthe openings of said second and third rows, the teeth of the sprocketwheel engaging the openings of said central row being substantiallybigger than the teeth of said sprocket wheels engaging the second andthird rows of openings.
 7. In a snowmobile as defined in claim 6,wherein said front drive axle supports one sprocket wheel for rotationtherewith, the teeth of said sprocket wheel engaging the central row ofopenings: wherein the rear idler axle supports a pair of sprocketwheels, the teeth of which engage the second and third rows of openings,respectively; and further comprising means on said rear axle for causingsaid rear sprocket wheels to rotate independently from one anotherthereby providing an anti-desynchronization effect therebetween.
 8. In asnowmobile as defined in claim 7, wherein said front drive axle furthersupports for rotation therewith a pair of sprocket wheels, the teeth ofwhich respectively engage the second and third rows of openings.
 9. In asnowmobile as defined in claim 8, wherein said rear axle furtherincludes a third sprocket wheel engaging the central row of openings andmeans for causing said third sprocket wheel to rotate on said rear axleindependently of said other sprocket wheels mounted on said rear axle.